A research expedition off the coast of Mexico in 1982 discovered a microbe living near hydrothermal vents deep in the sea, where temperatures approach the boiling point of water and the pressure can crush an ordinary submarine. Using the submersible vehicle Alvin, the researchers isolated the microbe and brought it back to the laboratory.

Fourteen years later, in 1996, scientists in Maryland sequenced its genome and found many genes that no one had ever seen. The organism, named Methanococcus jannaschii, is a type of archaea, a family of microbes thought to have evolved separately from plants and animals (eukaryotes), and also from bacteria (prokaryotes).

An analysis of the microbe’s genome supported the idea that the archaea represent a third “domain” of life. Some scientists had been making this case since the 1970s, but their evidence had been based on evolutionary studies involving small numbers of genes.

Not only was this the first member of the archaea to be sequenced, but it was also the first “extremophile” to be sequenced. An extremophile is an organism that lives in harsh environments such as the ice of Antarctica or hydrothermal vents at the bottom of the ocean.

Since 1996, the genomes of a number of extremophiles have been sequenced. Some of this research has led to the discovery of proteins in nature that can withstand high temperatures and have potential commercial applications.